I was of the understanding that every MB from '93 to '95 had the same wiring insulation that, given the right (or wrong!) conditions, would deteriorate. I think the key here is the conditions. Temperature seems to play a big part. Below a certain temperature there appears to be no problem but go above that temperature and you have problems. Wiring in the engine bay, particularly in areas close to the engine, deteriorates whereas elsewhere on the car it does not.

Here in Australia we definitely see the problem on engine wiring harnesses. Our wiring harnesses are different to those in North America or Europe to cater for our right-hand-drive cars yet obviously use the same insulation. I would imagine that the same wiring insulation was used irrespective of the intended destination for the car.

Possibly the climate in Canada results in slightly lower engine bay temperatures to those in The USA (or Australia). We find that the models with larger engines and more crowded engine bays (and presumably higher engine bay temperatures) are more prone to harness failures. W124s and W202s with the M104 (6 cyl) suffer the problem whereas those with the M111 (4 cyl) don't seem to (we got no V8 W124s). W140s (M104 & M119) also suffer the problem.

I recall hearing of engine wiring harness replacements on '93 to '95 MBs in many different countries. Maybe it is not such a big problem in the colder climates.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.